Immunology

lymphokines

Lymphokines comprise that subset of cytokines produced by T lymphocytes, whereas monokines are secreted by monocytes. Modern usage employs the more general term 'cytokine'.

Lymphokines include:
● colony-stimulating factors (CSFs), including GM-CSF
● interferons (IFNs) - IFNγ
● interleukins IL-1 to IL-8, IL-10, IL-13
● macrophage inflammatory protein-1 beta (MIP-1β)
● neuroleukin (lymphokine product of lectin-stimulated T cells)[s]
● osteoclast-activating factor
● platelet-derived growth factor (PDGF)
● transforming growth factor beta (TGFβ)
● tumour necrosis factor-alpha (cachectin) (TNFα)
● tumour necrosis factor-beta (TNFβ, lymphotoxin α, LT)

Actions of lymphokines include
● activates B cells, inhibits macrophage function – IL-10
● activation of neutrophils, eosinophils, and monocyte/macrophages – GM-CSF
● bone resorption – osteoclast activating factor
● bone marrow – growth and differentiation of immune cells – IL-3
● B cell growth and differentiation – IL-4
● B cell differentiation, activates some microphages (PMN) – IL-5
● costimulator of T cells, induces growth in B cells – IL-6
● inflammation, fever, catabolism and cachexia, activation of some microphages – TNFs
● hematopoiesis stimulators – IL-3, IL-7, GM-CSF
● macrophage-activating activity (MAF) – IFN-γ
● stimulates proliferation of activated T and B cells – IL-2
● inhibits T cell growth, activates macrophages – TGFβ

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plasma cells

Plasma cells are B lymphocytes that have been activated to differentiate and mature by CD4+ helper T lymphocytes. Activated B cells become either memory B cells or plasma cells, which secrete copious amounts of monoclonal antibodies against the original antigen that triggered the antigen presenting cells.

Affinity maturation is a process of affinity-selected differentiation and maturation of activated B cells. Repeated exposures to the same antigen provokes greater antibody ligating affinity in the antibody secreted by successive generations of plasma cells. Isotype switching, in response to signaling by specific cytokines, provides for a switch of production from IgM to other Ig isotypes following first exposure to an antigen. T cell-produced immune cytokines, such as interleukin-4 (IL-4), interferon-γ (IFN-γ), and TGF-β effect isotype switching.

Plasma cells are predominantly located in the bone marrow (0.2% to 2.8% of leukocytes) and are rarely found in the peripheral blood.(description of morphology)

Plasma cells are seen in abnormal numbers in multiple myeloma, plasma cell leukemia, Waldenström's macroglobulinemia, and MGUS (monoclonal gammopathy of uncertain significance).

[] tem plasma cell [] micrograph macrophage surrounded by normal plasma cells [] micrograph macrophage & plasma cells []

Tables  Fc receptors  Immune Cytokines  Immunoglobulins

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